Troubleshooting Common Home Radiator Problems

Common Radiator Problems

There are a range of problems associated with household radiators which you can troubleshoot fairly easily – some are small easy fixes, whilst others might require the services of a heating engineer.

We list the most common radiator problems and how to fix them in this handy guide. So if your radiator is not getting warm have a look at how to fix it in our remedies below.

Radiator is cool at the top but hot at the bottom

This is one of the most common problems that can happen with radiators and at one time or another most householders will have experienced this with one or several radiators. If the radiator is hot at the top but cold at the bottom it means that there is air trapped at the top of the radiator. Thankfully there is a very simply fix for this which will invariably fix the problem unless there is a more serious inherent problem.

To remedy you will need to bleed the radiator.

This involves taking a bleed key (these should be supplied with each radiator, but if not they can be picked up cheaply and easily at a hardware shop – some modern valves will also accept a flat-blade screwdriver), putting the key in the air vent at the side of the radiator towards the top and twisting the key anticlockwise until you hear air escaping. Make sure that you have a rag or absorbent paper towel with you at the time which should be held underneath the key or against the bleed air opening on more modern radiators, because eventually the hissing of the air escaping will stop and water will dribble – or in the case of combi-boiler systems (which are under higher pressure than gravity-fed systems)- spray out!

The water inside your central heating system is often dark and unpleasant depending on the age of the system and how well maintained it is, and has a very specific odour to it. If the water is black it is indicative of sludge or corrosion in the system and it may also stain wallcoverings or flooring and care should be taken to prevent this from happening. Once water starts to drip you should tighten the key again and any excess water will be caught by the rag. Once the radiator has been bled you should start to feel the heat in the radiator rising to the top within minutes so that you have a hot radiator from top to bottom.

You will generally find that the radiators higher up in the property will contain the most air.

Radiator is hot at the top but cool at the bottom

If the radiator is hot at the top but cool at the bottom is can mean that there is a sludge (specifically black iron oxide) build up in the bottom of the radiator. This is what is stopping the circulation and will need to be removed before the radiator will work to an optimum level again. To remove the sludge you could remove the radiator after closing the valves on either side where the pipework connects and take it into the garden and flush it through with a hosepipe. Chances are that if one radiator is affected the others will be too, and so you should consider repeating the process on the other radiators in the system too.

Another option is to add central heating cleaner or sludge removal liquid into the feed and expansion cistern, or directly into a radiator via an injection tool in a combi system. Always check that the product being used is suitable for the type of system in your home.

After a couple of days or in line with the product directions if different, the system should be drained, refilled and bled. Once flushed but before refilling entirely, it would be wise to add a corrosion inhibitor such as Fernox to minimise future corrosion problems and keep your central heating system running as efficiently as possible. Again these are added ini the same manner as the cleaning agent. It will save you a good deal of money on your gas bill in the longer term and will help prevent issues with sticking valves and leaking, corroded radiators.

All radiators in the house are cold

This could indicate that there is a build-up of sludge throughout all the radiators which needs to be flushed out as described above.

Radiators on the top floor of the house are hot but the lower floors they are cold

If this occurs it is usually a sign that there is a pump failure within the system.

Radiators on the top floor are cold

This could mean that the feed and expansion cistern is empty or the ball valve might be faulty. To test this you could refill the cistern with just enough water to float the ball when the water that is in the system is cold enough.

Upstairs radiators are cool except when hot water is selected on the programmer

If you have a gravity feed central heating system and the radiators are cool but get hot when the hot water program is selected then the gravity check valve may have got stuck on the open setting. This valve should stop upstairs radiators from getting hot when only hot water is needed so if it is stuck on the open setting then the upstairs radiators will get hot when you don’t want them to and this will cost your money on your energy bills. In order to fix this you will need to get a central heating engineer or boiler engineer to replace the valve for you.

Central Heating Cover

If you are not confident in your ability to maintain and fix your own system you could consider British Gas Homecare, which for a small monthly fee will give you cover for your boiler and central heating heating system, and guarantee you an expert on-site as quickly as possible to fix your issues without the call-out charges that plumbers generally like to levy for the priviledge of having them turn up (if they turn up…) to take a look!

More information can be found here.